call and find out about an aarp medicare supplement insurance plan, insured by unitedhealthcare insurance company. like all standardized medicare supplement plans, it could save you thousands in out-of-pocket costs. call now to request your free decision guide. i've been with my doctor for 12 years. now i know i'll be able to stick with him. you'll be able to visit any doctor or hospital that accepts medicare patients. plus, there are no networks, and you never need a referral. see why millions of people have already enrolled in the only medicare supplement insurance plans endorsed by aarp. don't wait. call now. >>> this morning on "world news now," mystery gunman. who was the suspect who put on a mask and camouflage and opened fire in an oregon shopping center? >> this morning, the new clues from insiders and the latest leads from investigators. it is thursday, december 13th. >> announcer: from abc news, this is "world news now." >>> good thursday morning, everybody, i'm rob nelson. >> and i'm paula faris. we're going to get the latest on that deadly mall shooting investigation in our to